As wireless communication is widely used these days, traffic grows exponentially and demands of individual users for handling the increased traffic also grow. The higher the demand for handling the traffic is, the higher the bandwidth is, and high operating frequencies are required to use the high bandwidth. For this, a communication technology of a related art that uses ultra-high frequency spectrum (millimeter Wave or mmWave) has been proposed.
Signals of the ultra-high frequency band like the mmWave band have a Line of Sight (LOS) characteristic, and thus have a strong straightness and a weak transmittance. Accordingly, assuming that a user using the mmWave band has moved from outdoors to indoors, the user indoors may have difficulty performing communication using signals transmitted from an outdoor Base Station (BS). Thus, in the case of using the mmWave band, every room or every shadow area in which there are walls, humans, and electricity requires an apparatus for relaying the signal from the outdoor BS, e.g., a WiFi Access Point (AP). Thus, the communication technology has limits of being used only in a place where the WiFi AP is installed.
In the meantime, the WiFi technology does not suggest any handover scheme, and thus in a WiFi communication system, a User Equipment (UE) performs handover by scanning other APs, measuring Received Signal Strength Indication (RSSI) of a signal received from each scanned AP, and selecting an AP for handover from among the scanned other APs based on the respective RSSIs of the scanned APs.
However, since the UE may not know on which channel the other APs operate, the UE must scan all the channels for other APs and especially, active scanning requires many procedures as follows:
(1) The UE broadcasts a probe request message on an associated channel,
(2) APs receiving the probe request message send probe response messages, and
(3) The UE measures RSSI based on the probe response messages received from the APs.
The UE and APs may determine an AP for handover by performing the procedures (1) to (3), but the procedures (1) to (3) may increase handover time. Such an increase in handover time may cause packet losses and thus significant inconvenience for the user.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.